Phased Array Ultrasonic Measurement of Fatigue Crack Growth Profiles in Stainless Steel Pipes

2006 ◽  
Vol 129 (4) ◽  
pp. 737-743 ◽  
Author(s):  
L. Satyarnarayan ◽  
D. M. Pukazhendhi ◽  
Krishnan Balasubramaniam ◽  
C. V. Krishnamurthy ◽  
D. S. Ramachandra Murthy
Keyword(s):  
Stainless Steel ◽  
Fatigue Crack ◽  
Crack Growth ◽  
Phased Array ◽  
Potential Drop ◽  
Outer Diameter ◽  
Steel Pipes ◽  
Bending Load ◽  
Load Arrangement ◽  
Beach Marks

This paper reports experimental sizing of fatigue crack profiles that are initiated from artificially made circumferential starter notches in stainless steel pipes of 169mm outer diameter and 14.33mm thickness, which were subjected to cyclic bending loads in a four point bending load arrangement using two nondestractive evaluation (NDE) methods: (a) phased array ultrasonic technique and (b) alternating current potential drop technique. The crack growth estimated using the two NDE techniques were compared with the beach marks that were present in the fracture surface. A simulation study using the ray tracing method was carried out to model the ultrasonic wave propagation in the test specimen, and the results were compared with the experimental results.

Effect of Hydrogenated Water on Fatigue Crack Growth for Austenitic Stainless Steel in Simulated BWR Water Environment

2004 ◽  
Author(s):  
Li H. Wang
Keyword(s):  
Stainless Steel ◽  
Fatigue Crack ◽  
Cyclic Loading ◽  
Austenitic Stainless Steel ◽  
Fatigue Crack Growth ◽  
Water Chemistry ◽  
Crack Growth ◽  
Growth Stage ◽  
Transgranular Fracture ◽  
Cyclic Loading Condition

Fatigue crack growth rates (FCGR) of sensitized austenitic stainless steel (SS) were measured in simulated BWR water at 288 °C using compact tension specimens under different cyclic loading modes, including saw-tooth, trapezoidal and constant loading pattern. This study tested sensitized SS in normal water chemistry (NWC) and hydrogen water chemistry (HWC) respectively, and attempted to clarify the effect of low electrochemical corrosion potential on the FCGR of sensitized stainless steel. Significant environment effects on FCGR of sensitized stainless steel were observed in both water chemistries when compared with air fatigue curve. The pronounced suppression effect of HWC on crack growth in statically sustained load was not observed in cyclic loading condition. ASME curve doesn’t seem to be conservative and could not bound all the FCGR data tested in this study. In contrast, all of the measured FCGR data were bound by the JSME disposition curve. PLEDGE model proposed by General Electric reasonably predicted the FCGR of sensitized SS in NWC, but underestimated the FCGR in HWC. ANL’s superposition model successfully estimated the FCGR measured in both water chemistries. The fractography exhibited transgranular fracture mode during the crack initiation and growth stage. No differences in the appearance of fracture surface were observed in HWC and NWC. Only in very high DO environments, the sensitized 304 SS exhibited the mixed mode of intergranular and transgranular during growth stage.

Effects of a Single Overload on Fatigue Crack Growth of Type 316 Stainless Steel

2021 ◽  
Author(s):  
Koji Miyoshi ◽  
Masayuki Kamaya
Keyword(s):  
Growth Rate ◽  
Stainless Steel ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Opening ◽  
Constant Amplitude ◽  
Single Overload ◽  
Tensile Overload

Abstract The effect of a single overload on the fatigue crack growth rate was investigated for Type 316 stainless steel. Fatigue crack growth tests were conducted by controlling strain and load. Tensile and compressive overloads were applied during constant amplitude cycling. The overload ratio, which was defined as the ratio of overload size to baseline constant amplitude, was also changed. The constant amplitude tests were conducted at the strain or the stress ratio of −1.0 which was defined as the ratio of the minimum value to the maximum value. The crack opening point was obtained by the unloading elastic compliance method. The crack growth rate increased after the single compressive overload. The accelerating rate increased with the overload ratio. In contrast, not only the acceleration but also the retardation of the crack growth rate was observed for some tensile overload cases. The crack growth rate increased for relatively small tensile overload cases and decreased for relatively large tensile overload cases. The change in the crack opening level was examined. The crack growth rates after tensile and compressive single overloads correlated with the effective strain and stress intensity factor ranges both for load and strain controlling modes.

Fatigue Crack Growth Properties of a Cryogenic Structural Steel at Liquid Helium Temperature

1996 ◽  
Vol 118 (1) ◽  
pp. 109-113 ◽  
Author(s):  
Shinji Konosu ◽  
Tomohiro Kishiro ◽  
Ogi Ivano ◽  
Yoshihiko Nunoya ◽  
Hideo Nakajima ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Fatigue Crack ◽  
Austenitic Stainless Steel ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Liquid Helium ◽  
Liquid Helium Temperature ◽  
Small Scale ◽  
Helium Temperature ◽  
Growth Properties

The structural materials of the coils of superconducting magnets utilized in thermonuclear fusion reactors are used at liquid helium (4.2 K) temperatures and are subjected to repeated thermal stresses and electromagnetic forces. A high strength, high toughness austenitic stainless steel (12Cr-12Ni-10Mn-5Mo-0.2N) has recently been developed for large, thick-walled components used in such environments. This material is non-magnetic even when subjected to processing and, because it is a forging material, it is advantageous as a structural material for large components. In the current research, a large forging of 12Cr-12Ni-10Mn-5Mo-0.2N austenitic stainless steel, was fabricated to a thickness of 250 mm, which is typical of section thicknesses encountered in actual equipment. The tensile fatigue crack growth properties of the forging were examined at liquid helium temperature as function of specimen location across the thickness of the forging. There was virtually no evidence of variation in tensile strength or fatigue crack growth properties attributable to different sampling locations in the thickness direction and no effect of thickness due to the forging or solution treatment associated with large forgings was observed. It has been clarified that there are cases in which small scale yielding (SSY) conditions are not fulfilled when stress ratios are large. ΔJ was introduced in order to achieve unified expression inclusive of these regions and, by expressing crack growth rate accordingly, the following formula was obtained at the second stage (middle range). da/dN = CJ ΔJmJ, CJ = AJ/(ΔJ0)mJ, where, AJ = 1.47 × 10−5 mm/cycle, ΔJ0 = 2.42 × 103N/m.

Elastic-Plastic Fracture Mechanics Analysis of Cast Stainless Steel Pipes (Influence of Axial Load on Z-Factor of Pipes With Circumferential Crack Under Bending Load)

2013 ◽  
Author(s):  
Masayuki Kamaya ◽  
Kiminobu Hojo
Keyword(s):  
Stainless Steel ◽  
Axial Load ◽  
Power Plants ◽  
Structural Integrity ◽  
Term Operation ◽  
Steel Pipes ◽  
Integrity Assessment ◽  
Plastic Failure ◽  
Elastic Plastic ◽  
Bending Load

Since the ductility of cast austenitic stainless steel pipes decreases due to thermal aging embrittlement after long term operation, not only plastic collapse failure but also unstable ductile crack propagation (elastic-plastic failure) should be taken into account for the structural integrity assessment of cracked pipes. In the ASME Section XI, the load multiplier (Z-factor) is used to derive the elastic-plastic failure of the cracked components. The Z-factor of cracked pipes under bending load has been obtained without considering the axial load. In this study, the influence of the axial load on Z-factor was quantified through elastic-plastic failure analyses under various conditions. It was concluded that the axial load increased the Z-factor; however, the magnitude of the increase was not significant, particularly for the main coolant pipes of PWR nuclear power plants.

scholarly journals The Influence of Ceramic Coating on Fatigue Crack Growth Behaviour of X17CrNi15-2 Stainless Steel

Engineering ◽  
2020 ◽  
Vol 12 (02) ◽  
pp. 140-149
Author(s):  
Ran Li ◽  
Wenshu Wei ◽  
Shoubin Li ◽  
Rui Zhao ◽  
Hao Liu ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Ceramic Coating ◽  
Growth Behaviour ◽  
Crack Growth Behaviour
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